Singer S M, Elmendorf H G, Conrad J T, Nash T E
Laboratory of Parasitic Diseases, National Institutes of Health, Bethesda, Maryland 20892-0425, USA.
J Infect Dis. 2001 Jan 1;183(1):119-24. doi: 10.1086/317659. Epub 2000 Nov 16.
Immune evasion is frequently cited as the main reason for antigenic variation in pathogenic microorganisms. To better understand the role of switching of variant-specific surface proteins (VSPs) in Giardia lamblia-host interactions, antigenic variation during infections of mice and gerbils was examined, using clones that predominantly expressed unique VSPs. As expected, VSPs were selected against during infections of immunocompetent hosts. In contrast, in immunodeficient hosts, some VSPs were selected for and others were selected against. These diverse patterns of selection demonstrate that there are host-VSP interactions that exert both positive and negative selective pressures on parasites, independent of the adaptive immune response. Furthermore, selection was dependent on both the particular VSP and the host. Thus, the large number of VSP genes in G. lamblia may allow the parasite to infect multiple different hosts, and antigenic variation could be a mechanism to expand the parasite's host range.
免疫逃逸常被认为是致病微生物抗原变异的主要原因。为了更好地理解变异特异性表面蛋白（VSPs）转换在蓝氏贾第鞭毛虫与宿主相互作用中的作用，利用主要表达独特VSPs的克隆，检测了小鼠和沙鼠感染过程中的抗原变异。正如预期的那样，在免疫健全宿主的感染过程中，VSPs会被淘汰。相比之下，在免疫缺陷宿主中，一些VSPs被选择保留，而另一些则被淘汰。这些不同的选择模式表明，存在宿主与VSP之间的相互作用，这种相互作用对寄生虫施加了正向和负向的选择压力，而与适应性免疫反应无关。此外，选择既取决于特定的VSP，也取决于宿主。因此，蓝氏贾第鞭毛虫中大量的VSP基因可能使该寄生虫能够感染多种不同的宿主，而抗原变异可能是扩大寄生虫宿主范围的一种机制。
